Speedometer.



A. A. CANTON SPEEDOMETER.

APPLICATION FILED ocr. 29. 1914.

2 SHEETS-SHEET '2.

ALLEN A. CWNTON, 0F hl'Eiiv YORK, N. Y., ASSIG-NOR T0 THE EVICE TESTING COMPliiNY,

A CORPORATION OF CONNECTICT.

Application filed october $9, 1914.

17 b IZZ 'whom t may concern Be it known that I, ALLEN A. CANTON, a citizen of the United States'of America, and a resident of the city, county, and State of New York, have invented certain new and useful ln'iin'ovements in Speedometers, of which the following is a specification.

rllhis invention relates to improvements in electrically operated speedometers and the object of the invention is to provide certain improvements or novel features in combi` nation with the yspeeiilometer o'r other Siinilar apparatus whereby to simplify the operation thereof and with a view of rendering its operation more certain and dependable. i

With these and other objects in view, all of which will appear as pthis specification proceeds, the invention cohiprises the eleinents and parts arranged hind combined with a speedometer as hereinafter set 'forth and as show-n in the accompanying draw inns in which-- Figure 1 is a wiring the invention. Fig, 2 the coininutatoi. Fig. central sectional view diagram ilhlstrating a detail view of 3 is a,substantially of theV speedometer,

Referring to the drawing the numeral 10 indicates the core of an electroinagnet, prcf erably circular in form and having` the poles 11 between which are wound the coils 1Q.

13 represents the armature for the electroinae'net and which is preferably composed of soft iron laminal as shown.

'The coils oi the ehatroinagnct are connected serially to the segments l5 of a co1nmutalor 1G which is suitably secured to a bracket 17 which may form a bearing for the shaft 1li, the speed of which is to be measured.

179, 19 are brushes mounted on a brush Specifieaton of Letters Patent.

iPa/tentod fing.. @@ttliit serial no. assisi.

port of the armature 13. The boss is apen cured at Q8. Secured to the armature and passing through the aperture Q8 there is mounted a leaf spring -or vibrating,r Contact lever Q9 normally in contact with the ad` just-able contact point 30 suitably mounted in the bottom of the casino. lever 2S) is arranged diametrically as appears from Fig. 1 with its free end 3l projectingin under one of the aforesaid poles l1.

32 is a suitable resistance mounted in inductive relation to the electromagnet l0-i-ll-`l2.

` The circuit between the battery 2l and the brushes 1D referred to above may now be traced by i vvay of the wire 33 to the bindingl post 34- of the contact lever 29, through the latter to contact point 3G and back to the commutato and battery by way of wires 35 and 36. The resistance 32 is connected in shunt .between 'the wires and by means of the wires 37 and 38.

3S) are sliding contacts for supplying the brushes 19 with current in the usual 1nanner. l A speed indicator l0 of aluminum or similar material is mounted to rotate between the armature 13 and the electromagnet 10h12 so as to cut the magnetic lines of force between these two elements. for which purpose the indicator is provided with a skirt or cylinder as shown. c The indicator is further provided with a scale Ll1 which Vis read .through the window 2G with reference to a fixed niark 42 on the cover of the easing. The pivot 43 of the indicator has its bearings in the cover and the armature as shown.

ist is a hair spring'which tends to keep the indicator in Zero position and i5 repre- The Contact sents stops tor limitingthe movement of the indicator.

'lhe operation-is as follows;A The rotation of the shaft 18 produces a rotating magnetic field between the electromagnet and the armature and which in turn imparts a rotative tendency to the indicator in the 'direction of rotation of said field and in di rect proportion 'to the rotative speed of the shaft 1S, such tendency, however, being opposed by the spring Livin such a proportion with respect to the magnetic effect-created by the elcctroinagnet as to cause 'the indicator to revolve 'to an extent in direct proportion to the speed of the shfifft 18, so that,

when the indicator scale is properly calibrated, the exact speed of the rotation of the shaft will he indicated with reference to the fixed niark 42. The stops 45 prevent the indicator from making more than. one revolution as is obvious., Hence, the speed of the shaft 18 may be read directly by means oi the scale 41 on the indicator because the movement of the latter is in di- Irect proportion to said speed. This condition, however, exists only while the strength of the rotating magnetic field remains practically constant. Variations therein, due to yvariations inthe voltage of the current from the source 21, influences the movement of the indicator asis obvious and the latter does not then'correctly indicate the speed of the operating shaft 18. An increase in` voltage beyond that for which the apparatus is designed strengthens the magnetic field and will causea too fast movement of the indicator and vice versa. It will be noted,

, therefore, that the construction illustrated` andI described provides a. regulating mechanism to eliminate from the operation of the vspeedometer such inaccuracies orirre'gulari- .of therlever 29 and contact point 30. lVhen,

however, the voltage increases, the magnetic strength'aif the poles 11 isincreased and the it'reeend 11 of the lever 29 is attracted by thev pole immediately above it. This breaks the Contact at 30 and cuts the resistance into the circuit to decrease the voltage for the speedometer, the current passing from the battery, through wire 33, wire. 3T

to the resistance 32, through the latter and y by wire 38 to wire 35, through the commutator, the coils 12 and back to the battery by wires 22 and 3G. The resistance is further wound in the opposite direction to that of the coils l2 and thus also acts to dampen or cut down vthe magnetic strength of the electromagnet when the 'resistance is in the circuit. `When the voltage decreases to normal, the contact lever itself acts as a spring and again makes contact at 30 so as to cut the resistance out. rlhus the variations in voltage and in ,the strength of the rotating magnetic field automatically operates the lever 29 and causes a vibration ot' the latter .to malie and break contact with the contact point 30 to govern the relation of the resistance to the circuit and maintain the voltage practically construit for the speedometer.

When the battery is the sole'source of current supply it is generally overcharged so that it will discharge current with a higher voltage than desired for operating the speedometer, in which case the resistance will be cut into the circuit at the start of the operation, but will be cut out automatically as the voltage drops. Frequently, however, a geneirptor 50 is connected serially with the battery to charge the latter in which case the .resistance lwill be out into or out of the circuit in response to variations in voltage.

51 represents diagrammatically a speed l controlled switch and 52 a reverse relay such as are usual and well known in the art.

From the foregoing it is clear that means have been provided within the speedometer mechanism itself for eliminating the disturbing influence in the operation of the, speedometer due to variations in the voltage.

I do not wish to be iindeistood as limiting my invention to the embodiment illustrated and described, but that I claim all such modifications and variations as properly come within the principle of the invention and the scope of the appended claims.

I claim 1. The combination of an electrically operated speedometer mechanism, means for supplying current to the sinne and including a circuit, a resistance for the, lutter and means in said speedometer mechanism and responsive to the. Voltage in said circuit for governing the relation of the said resistance to the circuit.

v2. The combination of an electromagnet,

an armature. an indicator member between the latter and said electromagnet, a circuit for supplying current to the. said electromagnet, ya resistance for said cii'euit and a contact lever mounted on said armature and 'responsive to the voltage in said circuit for governing the .relation of the resistance to the circuit.

3. The combination of a casing, a speed indicator mounted to rotate therein. a shaft` electric means within said casing for operating said indicator and controlled by the speed of the said shaft, a circuit for supplying current to said 'electric means. a resistance for said circuit mounted within said ci sing and mechanism supported within theI latter and responsive to the. voltage in said circuit t'or governing the relation of the said resistance to the circuit.

Signed at New York, Y., this 23rd day of October, 191i. y

ALLEN A. CANTON.

Witnesses:

' lVAi/.rnn Si lVliiii'inN, IVAN' Koniosnmio. 

